ALIF is a spinal fusion procedure that utilizes an anterior (i.e. frontal) approach through the abdominal region to fuse adjacent vertebrae of the lumbar spine. The intervertebral disc is removed using appropriate rasping and grasping tools and replaced with a cage device and/or bone graft after appropriate distraction and spacing tools are used to restore the normal height of the intervertebral space. ALIF is preferred when either one or multiple spinal levels are being fused and one or multiple intervertebral discs must be removed, and may be performed in conjunction with a posterior decompression (i.e. laminectomy) and/or the placement of stabilizing instrumentation (i.e. screws and rods, plates, etc.). Because during ALIF the spinal nerves and other neurologic structures do not have to be retracted, wide access to the intervertebral space(s) of interest is provided without unacceptable risk of neurologic injury. ALIF is used to treat a variety of painful spinal conditions, such as spondylolisthesis and degenerative disc disease, among others.
Conventional ALIF cage devices typically include some sort of retention mechanism to hold them securely in the intervertebral space. Such retention mechanisms include biting and locking structures that engage the endplate(s) of the vertebral body or bodies of interest, screw assemblies that engage the vertebral body or bodies of interest, plate structures that engage the vertebral body or bodies of interest, etc. All of these retention mechanisms, however, suffer from the shortcomings that they are difficult to place, difficult to deploy, and/or tend to allow the associated cage device and/or bone graft to shift over time and thus fail to adequately maintain the normal height of the intervertebral space, for example. Thus, what is needed in the art is an improved ALIF cage device having an improved retention mechanism.